A plastic level is known from AT-U-006 006. In order to construct this level in a relatively long manner without accepting impermissible distortion, the level is molded using the internal gas pressure procedure.
It is also known how to produce levels by means of a foam injection molding procedure, in order to minimize the distortion. The disadvantage of this procedure, however, is a lower surface quality, so that basic reprocessing is required.
Known from DE-U-77 04 713 is a level whose body consists of a plastic profile. Metal inserts, which are molded or inserted into the plastic profile, extend inside the plastic profile basically over the entire length of the level body. There is also the possibility of constructing the level body by extrusion, wherein the metal inserts are pulled into the body by jets. In another embodiment, a hollow box profile is used to construct the level body, on the interior side of which profile recesses can be present into which metal inserts can be placed.
The metal inserts can also be molded in during the injection molding of the level body or can be pushed into the previously named recesses after molding the body of the level.
A level body is produced by injection molding according to DE-T-699 05 557. In order to fix the bubble level, it is accepted into a metal frame, which can be placed in an injection molding tool.
A level made of a thermoset resin mixed with glass particles is known from DE-T-690 22 596.
A level is known from U.S. Pat. No. 3,921,306 and U.S. Pat. No. 3,889,353 whose body is made of high density urethane foam. Extending along the working surfaces of the level all the way to the edges are metal inserts, which have a Y-shaped geometry in a cut-away view in the area of the working surfaces. Because of the profile geometry and the course of the metal frame, recesses for receiving the bubble levels are provided exclusively in the rib of the level.